Two types of well defined primary dissociated cell cultures from 7-9 day old rat cerebellum, one enriched in neurons (excitatory granule cells and inhibitiory stellate and basket cells) and the other containting glia (type I astrocytes) a specifically designed culture perfusion chamber, high performance liquid chromatography (HPLC), and biochemical techniques will be used to, 1) identify the pharmacological characteristics and cellular origins of stimulus-evoked and spontaneous release/efflux of the endogenous neurotransmitter and neuromodulatory substance aspartate, glutamate, adenosine, GABA and taurine. 2) investigate the roles of the signal transducing system, protein kinase C, Ca2+-calmodulin and inositol phospholipid metabolism which through ligand-receptor interactions may produce and regulate the release of endogenous aspartate, glutamate, adenosine, GABA and taurine. Contingent upon the accomplishment of these aims, it will perhaps then be possible to study the detailed pharmacology of in vitro CNS development, meaningfully test the in vitro effects of new drugs on cultured CNS cells, and examine the role of afferent input on cerebellar development in vitro. A detailed determination of the contributions of specific cell types to the composite pharmacology of the cerebellum is our major long-term goal.